.center{
  padding: 20rpx;
  display: flex;
  flex-direction: column;
}
.aa{
  position: fixed;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 100rpx;
  display: flex;
  justify-content: center;
  align-items: center;
  /* 底部安全距离 */
  padding-bottom:env(safe-area-inset-bottom);
  padding-bottom:constant(safe-area-inset-bottom);
  }
  .add_button{
    width: 90%;
    /* margin-top: 74rpx; */
   
  }